Aggregate Size Research Articles

Compact modeling of highly excited linear aggregates using generalized quantum particles

Calculation of nonlinear spectra of chromophore aggregates using response function theory when the number of contributing chromophores is large, and the level of excitation is high is extremely complicated. The main limitation is due to the exponential growth of computational time due to the aggregate size and number of excitations when considering an arbitrary excitation intensity. Non-perturbative calculation of spectra in this case becomes advantageous. We revisit our proposed model with exciton - exciton annihilation terms and apply it to large aggregates. We generalize the equations for both paulions and bosons with a parameter that allows smooth transition from one description to another. Intermediate statistics may also be valuable as molecular electronic excitations do not strictly obey either boson or paulion statistics. Specific approximations allow efficient calculation of pump-probe spectra for a large J aggregate.

Investigation of aggregate gradation on air voids distribution in porous asphalt concrete using X-ray CT scanning images

Porous asphalt concrete (PAC) is typically used as a paving material for porous asphalt pavement in rainy areas due to its abundant interconnected pores structure. Not all interconnected pores in PAC are valid for permeability, mainly influenced by the composition of aggregate gradation. The main purpose of this paper is to investigate the effect of aggregate gradation on pores structure distribution in PAC by X-ray computed tomography (CT) system and digital image processing (DIP) techniques. The distributions of porosity, number and average equivalent diameter of air voids in middle part are much more evenly compared to the both ends in PAC specimens, accounting for about 70 % of the total of specimen height. The average equivalent diameter of interconnected air voids mainly ranges from 0.5 mm to 5 mm in PAC, accounting for about 80 % of the total numbers. For PAC with similar porosity, the larger the normal maximum aggregate size (NMAS), the less the number and the larger the average equivalent diameter of air voids (interconnected air voids), the smaller the difference between the interconnected porosity and porosity. For PAC with same NMAS, as the porosity increase, the number and average equivalent diameter of air voids (interconnected air voids) are respectively decreased and increased gradually, the difference between the interconnected porosity and porosity is also showed a decreasing trend. And then, the correlated equation is established among porosity, interconnected porosity and the composition of aggregate gradation. The distribution of air voids (interconnected air voids) size could be well described by the two-parameter Weibull model, and the relationships are explored and developed between Weibull model parameters and the composition of aggregate gradation.

Stability and heavy metals accumulation of soil aggregates under different land uses in the southwest coastal Bangladesh

Agricultural soil contamination is increasing day-by-day and becoming a major problem over the globe. Trace elements accumulation in the bulk soil is frequently documented, however, there is no precise mechanism of their distribution in the different soil aggregates level. We collected twelve composite soil samples from banana fields, fallow land, rice cultivated with pond water (rice field-I), and rice cultivated with rain water (rice field-II). We separated soil samples into four different size of aggregates (4-2, 2–0.25, 0.25–0.053, <0.053-mm) and then, aggregate stability (MWD), soil organic carbon (SOC), and heavy metals content (Pb, Cd, Cr, As, Fe, Mn, Zn, Ni, Co, Cu) in the soil samples were measured with different techniques. Results showed that MWD was higher in the rice-based land use, which was significantly contributed by SOC (p < 0.001). The concentration of Pb, As, Cd, Fe, and Mn were increased, while Cu and Zn concentration were reduced with increasing aggregate size (p < 0.05). In contrast, aggregate size did not influence on Ni and Co accumulation (p > 0.05). Moreover, macroaggregate acted as an accumulator for Fe, Mn, and As, while all the aggregate fractions acted as accumulators for Cu and Zn. Our study indicated that MWD, SOC, aggregate size and composition, and metal species were the controlling factors of trace elements accumulation and distribution in the various sizes of soil aggregates.

TREATMENT FOR REMOVING ZN COMPOUNDS FROM SILICA-FILLED VULCANIZED RUBBER AND ANALYSIS OF SILICA AGGREGATE DISPERSION

ABSTRACT Treatment of silica-filled rubber vulcanizates with a diethyl ether/concentrated hydrochloric acid solution for 96 h at room temperature can remove most Zn compounds smaller than approximately 90 nm, which account for most of the residual ZnO, rubber-soluble Zn compounds and ZnS resulting from crosslinking reactions of by-products. However, a very small number of giant ZnO particles of a few micrometers in size remain after such treatment. In the silica-filled SBR matrix treated for 96 h, a significant increase in crosslink density and Young’s modulus was observed due to crosslinking reactions after HCl was removed from HCl-added rubber molecules. This increase in crosslink density was accompanied by an increase in the surrounding layer of bound rubber closest to the silica of the two bound rubber layers around it and a decrease in the rubber matrix of the same volume. It is inferred that there was little change in the aggregate structure of the silica due to these volume changes. Alternatively, ultra-small X-ray scattering measurements of the treated samples showed shoulders derived from silica aggregates and clear high-resolution X-ray computed microtomography (X-ray CT) images were obtained due to the removal of Zn compounds smaller than approximately 90 nm in size. The relationship between these shoulders and the size of silica aggregates obtained by X-ray CT imaging was qualitatively consistent, and it was not affected by the presence or absence of bis-(3-triethoxysilylpropyl) tetrasulfide and 1,3-diphenylguanidine, but was dependent on the rubber type. The distance between nearest neighbor particles of silica aggregates, determined by X-ray CT imaging, also depended on the types of rubber.

Influence of aggregate size on relative velocity change of high-frequency ultrasound in progress of concrete curing

Previous research revealed that wave interferometry can be more effective than existing ultrasonic techniques in monitoring the strength development of early-age concrete. To improve its accuracy, this study aims to examine the impact of aggregate size on the relative velocity change of high-frequency ultrasound during the concrete curing process. Concrete cubic specimens with 150 mm sides were prepared using two different maximum aggregate sizes, 4.75 mm and 20 mm. These specimens were subjected to water curing for the first 28 days, followed by air curing until 150 days. Ultrasonic tests employing a 1 MHz frequency were performed throughout the curing process, and the measured signals were analyzed by applying wave interferometry techniques. The test results suggest that the influence of aggregate size was evident in both the initial water curing and the subsequent air curing. During the initial curing, the specimen with larger aggregates exhibited a greater increase in relative velocity change. Thereafter, the velocity change decreased during the subsequent air curing in both specimens. Based on the results, the correlation between relative compressive strength and relative velocity change was proposed considering the maximum aggregate size. The findings offer insights into the use of ultrasonic methods to evaluate the characteristics of early-age concrete.

Smooth vetch covering alters soil aggregate microbial metabolic limitations in citrus orchards

Green manure covering alters the supply-demand relationship between soil resources and microorganisms by improving soil structure and increasing carbon inputs. However, it remain unclear how soil microorganism respond to the imbalance between resources and demands at the aggregate scale. The present study analyzed the stoichiometric ratios of organic carbon, nitrogen, and phosphorus nutrients, microbial extracellular enzyme activities, and biomass in large macroaggregates (LMA, 2–8 mm), small macroaggregates (SMA, 0.25–2 mm), and microaggregates (MIA, < 0.25 mm) under smooth vetch covering. The relationship between microbial carbon use efficiency and nutrient restriction in soil aggregates was elucidated and the alteration was revealed in microbial metabolic pathways and carbon sequestration functions within soil aggregates under green manure covering. The results showed that: (1) Smooth vetch covering significantly increased the C: N resource imbalance (ln(MBC: MBN)/ln(SOC: TN)) in soil aggregates from 0.50 to 0.69, and thus increased the nitrogen requirement of soil aggregates. However, the N:P resource imbalance (ln(MBN: MBP)/ln(TN: TP)) decreased from 2.25 to 1.78, especially in microaggregates. (2) To mitigate the limitation imposed by nitrogen availability at the aggregate level, microorganisms have ramped up the activity of C- (46.72 %–98.64 %), N- (2.32 %–121.00 %), and P- acquiring enzymes (119.11 %–187.78 %). Nevertheless, the spatial heterogeneity inherent in soil aggregates, characterized by varying particle sizes, has led to a pivotal shift in microbial nutrient limitation. As soil aggregate size diminishes, the primary constraint on microbial activity transitions from nitrogen limitation to phosphorus limitation, reflecting the dynamic interplay between soil structure and nutrient availability. (3) In addition, smooth vetch covering increased the microbial carbon use efficiency of soil aggregates, and it increased with the increase of the particle size of soil aggregates: LMA (178.80 %) > SMA (147.23 %) > MIA (9.99 %). Microorganisms allocated more energy to generate biomass instead of obtaining limiting nutrient elements. These results indicate that smooth vetch covering could increase the organic carbon content of soil aggregates. In addition, in order to adapt to nutrient imbalance, soil aggregates microorganisms choose a “egoistic” metabolic pathway, which alleviates nutrient limitation and assimilated more energy and nutrients into their own biomass and reduces the release of organic carbon. It is evident that integrating Vicia villosa Roth var. glabresens Koch as a ‘green manure’ in orchards serves a dual purpose: it mitigates the environmental impact of chemical fertilizers while simultaneously promoting soil carbon sequestration. This approach offers a robust theoretical framework for achieving the harmonious integration of ecological sustainability and economic viability in economic forestry, such as citrus orchards.

PHYSICOCHEMICAL CHARACTERISATION OF SUVARNA BHASMA AND SUVARNA PRASHA USING ADVANCED TECHNIQUES

Background: Suvarna Prashana is an ancient Indian practice that boosts immunity, intelligence, memory, complexion, and virility and prevents infections in children. However, the characterisation of the drug is very limited. Material and Method: In this study, the physicochemical characterisation of Suvarna Bhasma is done with Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive Xray Analysis (EDAX ), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Suvarna Prash containing 15 mg of Suvarna Bhasma mixed with 0.25 ml of ghee and 0.75 ml of honey is characterised with Fourier Transform Infrared Spectroscopy (FTIR) with Suvarna Bhasma. Results: SEM revealed that gold particles of Suvarna Bhasma ranged from 27 nm - 8.1 µm and formed spherical aggregates of varied sizes with rough surfaces. EDAX suggested that Suvarna Bhasma contained Gold (86.3%), Oxygen (3.14%), and Carbon (10.52%). TEM reported that the particle size ranged from 2.2 to 18.9 nm, which existed in polycrystalline form as suggested by XRD. XPS confirmed the elemental state of gold Au(0), Silver-Ag +oxidation state, Carbon C-C, C=O, and C-N, where carbon is bonding with carbon, oxygen and nitrogen. FTIR revealed that Suvarna Bhasma alone had a single functional group of alkynes. When Suvarna Bhasma was triturated with honey and ghee, many functional groups were added to Suvarna Bhasma, i.e. fats, carbohydrates and amino acids. Conclusion: In this novel study, FTIR of Suvarna Prasha is reported for the first time, and it can be used as a fingerprint for drug identification. Also, it proves that Suvarna Bhasma, used in the current study, is a pure form of gold without heavy metals like mercury.

Application of machine learning technique for a fast forecast of aggregation kinetics in space-inhomogeneous systems

Modelling of aggregation processes in space-inhomogeneous systems is extremely numerically challenging since complicated aggregation equations, Smoluchowski equations, are to be solved at each space point along with the computation of particle propagation. Low rank approximation for the aggregation kernels can significantly speed up the solution of Smoluchowski equations, while the particle propagation could be done in parallel. Yet the numerics with many aggregate sizes remains quite resource-demanding. Here, we explore the way to reduce the amount of direct computations by replacing the actual numerical solution of the Smoluchowski equations with the respective density transformations learned with the application of one of machine learning (ML) methods, the conditional normalising flow. We demonstrate that the ML predictions for the space distribution of aggregates and their size distribution require drastically shorter computation time and agree fairly well with the results of direct numerical simulations. Such an opportunity of a quick forecast of space-dependent particle size distribution could be important in practice, especially for the fast (on the timescale of data reading) prediction and visualisation of pollution processes, providing a tool with a reasonable trade off between the prediction accuracy and the computational time.

Soil macroaggregate-occluded mineral-associated organic carbon drives the response of soil organic carbon to land use change

Understanding land use effects on carbon sequestration in various soil fractions is vital to mitigating climate change and restoring soil functions. The objective of this study was to explore the effects of land use on soil organic carbon (SOC) fractions in different soil types. For this purpose, we studied the effects of long-term (>20 years) land use including dryland pasture (DP), irrigated pasture (IP) and irrigated cropland (IC) on SOC in water-stable aggregates, particle-size fractions, and their coupling relations at the surface soils (0–7.5 cm) in the Canterbury Plains, New Zealand. For each land use, three typical soil types with contrasting drainage levels (i.e. well drained Lismore soil, LIS; imperfectly drained Templeton soil, TEM; and poorly drained Waterton/Temuka soil, WAT) were selected. Macroaggregate-occluded mineral-associated organic carbon (M-MAOC) contributed to the majority of the total SOC difference and drove the response of SOC to land use change. On average, M-MAOC followed an order of IP > DP > IC. The effects of land use change from DP to IP and IC on M-MAOC varied, and these variations were dependent on soil type. The relative gain in M-MAOC with change in land use from DP to IP was the greatest in the well drained LIS soil, while both the relative and absolute loss in M-MAOC following the land use change to IC was the greatest in the poorly drained WAT soil. The interactive effects of managements (e.g. irrigation and cultivation) and soil type (e.g. soil water condition) on aggregate size distribution and macroaggregate-associated C concentration were important in explaining the responses of M-MAOC to land use change. This study advances the mechanistic understanding of total SOC dynamics in response to land use (changes) in different soil types. It also highlights the potential of M-MAOC to serve as a diagnostic fraction to reflect changes in total SOC, which may have application to global warming mitigation.

Single-Molecule Fingerprinting Reveals Different Growth Mechanisms in Seed Amplification Assays for Different Polymorphs of α-Synuclein Fibrils.

α-Synuclein (αSyn) aggregates, detected in the biofluids of patients with Parkinson's disease (PD), have the ability to catalyze their own aggregation, leading to an increase in the number and size of aggregates. This self-templated amplification is used by newly developed assays to diagnose Parkinson's disease and turns the presence of αSyn aggregates into a biomarker of the disease. It has become evident that αSyn can form fibrils with slightly different structures, called "strains" or polymorphs, but little is known about their differential reactivity in diagnostic assays. Here, we compared the properties of two well-described αSyn polymorphs. Using single-molecule techniques, we observed that one of the polymorphs had an increased tendency to undergo secondary nucleation and we showed that this could explain the differences in reactivity observed in in vitro seed amplification assay and cellular assays. Simulations and high-resolution microscopy suggest that a 100-fold difference in the apparent rate of growth can be generated by a surprisingly low number of secondary nucleation "points" (1 every 2000 monomers added by elongation). When both strains are present in the same seeded reaction, secondary nucleation displaces proportions dramatically and causes a single strain to dominate the reaction as the major end product.

Evaluation of Machine Learning and Traditional Methods for Estimating Compressive Strength of UHPC

This research provides a comparative analysis of the optimization of ultra-high-performance concrete (UHPC) using artificial neural network (ANN) and response surface methodology (RSM). By using ANN and RSM, the yield of UHPC was modeled and optimized as a function of 22 independent variables, including cement content, cement compressive strength, cement type, cement strength class, fly-ash, slag, silica-fume, nano-silica, limestone powder, sand, coarse aggregates, maximum aggregate size, quartz powder, water, super-plasticizers, polystyrene fiber, polystyrene fiber diameter, polystyrene fiber length, steel fiber content, steel fiber diameter, steel fiber length, and curing time. Two statistical parameters were examined based on their modeling, i.e., determination coefficient (R2) and mean square error (MSE). ANN and RSM were evaluated for their predictive and generalization capabilities using a different dataset from previously published research. Results show that RSM is computationally efficient and easy to interpret, whereas ANN is more accurate at predicting UHPC characteristics due to its nonlinear interactions. Results show that the ANN model (R = 0.95 and R2 = 0.91) and RSM model (R = 0.94, and R2 = 0.90) can predict UHPC compressive strength. The prediction error for optimal yield using an ANN and RSM was 3.5% and 7%, respectively. According to the ANN model’s sensitivity analysis, cement and water have a significant impact on compressive strength.

Green Human Resources Management Practices and Tertiary Institution Productivity in South West Nigeria

Abstract: Inadequate Implementation of Green human resources Practices in tertiary institutions in South West Nigeria has made the higher institution of learning to face challenges in integrating environmental conservatives policy in their operations. The study therefore examined the effect of green human resources practices on organizational productivity of tertiary institutions in Nigeria. The study adopted a cross- sectional survey research design with the aid of structured questionnaire. The population for the study are the employees of the all the six (6) Federal polytechnics in South Nigeria, totaling 5028. From this population, an aggregate sample size of 371 participants were selected using Taro Yamane sample size calculator where proportional allocation was used to select participants for inclusion per tertiary institution. Structural equation modeling using Smart-PLS 4.0 was used for data analysis; as results indicated that GIO ( , T-statistic = 3.512, p &lt; 0.05), GRCM ( , T-statistic = 8.385, p &lt; 0.05), and GRS ( , T-statistic = 4.711, p &lt; 0.05) have significant positive effects on organizational productivity. This highlights the importance of these green HR practices in enhancing productivity in the selected tertiary institutions in Southwest Nigeria. The study concluded that green human resources management practices is crucial in achieving optimal organizational productivity of the federal polytechnics in South West Nigeria. The study therefore recommended that the management of the federal Polytechnics in South West Nigeria should use environmental conservative employer branding to attract, select applicants and retain employees who have green orientation through a well-defined and circulated environmental sustainability human resources policy.

Mechanistic Fatigue Performance Evaluation of Stone Mastic Asphalt Mixtures: Effect of Asphalt Performance Grade and Elastic Recovery.

This study evaluates the crack performance of stone mastic asphalt (SMA) mixtures according to the performance of a modified asphalt binder, evaluated based on the asphalt performance grade (PG) and the elastic recovery of multiple stress creep and recovery (MSCR) according to AASHTO M 320 and T 350. The cracking performance of the mixture was evaluated using the asphalt mixture performance tester (AMPT) according to AASHTO T 378 and T 400 through dynamic modulus and direct tension cyclic fatigue tests. Furthermore, the recently developed viscoelastic continuum damage (VECD) theory was utilized to evaluate the cyclic fatigue index parameter (apparent damage capacity, Sapp) and the permissible heavy vehicle class. For performance evaluation, six modified asphalt mixtures were prepared and tested using SMA aggregate gradation with a nominal maximum aggregate size (NMAS) of 10 mm. The MSCR test results revealed that, of the six asphalt mixtures, the rubber-based PG76-28 exhibited the least initial strain and the highest elastic recovery. The dynamic modulus test results demonstrated that using a rubber-based modifier increased the elastic modulus at high temperatures and decreased it at low temperatures, thereby enhancing resistance to plastic deformation in the summer and reducing low-temperature cracking in the winter. Finally, the correlation between the Sapp performance index and the elastic recovery of modified asphalt and the number of direct tension cyclic loads until failure of the mixture was evaluated as 0.87 and 0.76, respectively.

Carbon in soil macroaggregates under coffee agroforestry systems: Modeling the effect of edaphic fauna and residue input

Crop diversification tends to favor the soil fauna community, soil aggregation, and consequently soil organic carbon (SOC) stock. Understanding the association between these attributes can help in understanding the dynamics of physical protection of soil organic matter. In this context, our study aimed to answer: (1) how does the edaphic macrofauna community and soil carbon and aggregate classes respond to two types of coffee agroforestry systems (coffee with Grevillea robusta and coffee with banana) and how these responses differ from native ecosystem; (2) how and to what extent are soil aggregation regulated by the complex structural interactions of plant residue input, SOC, and the soil faunal community? The work was conducted in the municipality of Planalto, state of Bahia, Brazil. Three systems were evaluated: agroforestry system of Coffee arabica L. with Grevillea robusta (CG); agroforestry system of Coffee arabica with Musa spp. (CB); and native forest (NF). Four plots were delimited in each system, in which dry fractionation of the soil was performed to obtain aggregates of classes >6, 6–4, 4–2 and < 2 mm. The macrofauna was sampled using the Tropical Soil Biology and Fertility Program method. The labile and total carbon of the soil and aggregates were determined and the carbon management indices were calculated. The CG and CB presented a greater amount of larger size aggregates (> 6, 6–4 and 4–2 mm) than the NF. The CB system provided more favorable conditions for the soil macrofauna. Despite this, both coffee agroforestry systems favored the occurrence of Oligochaeta. The CG was more favorable to maintain labile fractions of organic matter than the CB. The edaphic fauna show a close relationship with the formation of carbon aggregates and stabilization which was directly influenced by continuous input of plant residues in diverse coffee growing systems.

Formation mechanism and stability of egg white fluid gels under ultrahigh-pressure homogenization pretreatment and synergistic heating effect

The thermal sterilization process of protein beverages inevitably leads to the formation of insoluble thermal aggregates, greatly reducing the texture and taste of protein beverages. In this study, homogenized egg white (HEW) was obtained by ultrahigh-high-pressure (UHP) homogenization pretreatment of egg white (EW), and then a special egg white fluid gel (EWFG) was prepared by water bath heating. The results showed that the optimal conditions for preparing EWFG were three cycles at 20 MPa homogenizing pressure and heating in a water bath at 72℃ for 10 min. Under these conditions, the EWFG was a milky-white homogeneous liquid with an average particle size of about 560 nm. Measurements of the physicochemical properties of HEW and EWFG showed that the UHP homogenization treatment reduced the viscosity of HEW, decreased the particle size of protein aggregates, and increased the zeta potential, which altered the interactions of proteins during the subsequent heating process and facilitated the formation of homogeneous and dispersed EWFG. EWFG showed good stability at pH 6–10 and in low-concentration saline and medium-concentration sucrose solutions. The EWFG obtained by the present treatment is more suitable for factory-scale production and has great potential for protein beverage applications.

Property Enhancement of Recycled Coarse Aggregate and Its Concrete under CO2-Accelerated Curing Treatment.

The poor properties of recycled coarse aggregate (RCA) and recycled coarse aggregate concrete (RCAC) are considered key constraints hindering the reuse of this waste resource in marine engineering. The CO2-based accelerated carbonation method, which utilizes the alkali aggregate properties of RCA to achieve CO2 uptake and sequestration while significantly enhancing its properties, has attracted widespread attention. However, the degree of improvement in the properties of RCA under different initial moisture conditions (IMCs) and aggregate particle sizes (APSs) after CO2-accelerated carbonation remains unclear. Moreover, the quantitative effect of carbonated recycled coarse aggregate (CRCA), which is obtained from RCA samples with the optimal initial moisture conditions, on the improvement of RCAC under optimal accelerated carbonation modification conditions still needs to be studied in depth. For this investigation, a CO2-accelerated carbonation experiment was carried out on RCA samples with different IMCs and APSs, and the variations in the properties of RCA with respect to its IMC and APS were assessed. The degree of accelerated carbonation modification of RCA under different IMCs and APSs was quantified, and the optimal initial moisture conditions for enhancing the properties of the RCA were confirmed. By preparing concrete specimens based on the natural coarse aggregate, RCA, and CRCA with the best initial moisture conditions (considering the same concrete-water proportion), the effect of CRCA on the workability, mechanical properties, and durability of the corresponding concrete specimen was determined. The findings of this study can be used to effectively promote the sustainable development of marine science and engineering in the future and contribute to global dual-carbon goals, which are of great practical significance and scientific value.

Comparative analysis of soil organic carbon and soil properties in landscapes of Kerala: insights from the Western Ghats of India.

Soil organic carbon (SOC) is known to vary among different ecosystems and soilscapes, yet the degree of variation remains uncertain. Comparing SOC levels in undisturbed ecosystems like forests with those in gradually altered ecosystems can provide valuable insights into the impact of land use on carbon dynamics. This study aimed to evaluate the effects of different land uses on soil fertility parameters in the tropical region of Kerala, focusing on forests as well as cultivated agricultural landscape such as coconut, pepper, tapioca, acacia plantations, and mixed home garden cropping systems. Significant variations were observed among different crops and land use systems in terms of soil fertility. Forests exhibited the highest SOC content at 3.78 g kg-1,while acacia plantations showed the lowest at 0.76 g kg-1. Additionally, various soil properties such as different carbon fractions (e.g., humic acid, fulvic acid), total nitrogen, carbon, available nutrients, physical properties, aggregate size fractions, microbial biomass carbon, and spectral signatures differed significantly across the different land uses. These findings suggest a decline in soil fertility in altered ecosystems compared to adjacent forest soils, highlighting the vital role of forests in conserving natural resources and maintaining soil health. In addition, among the different landscapes studied, mixed cropping systems of home gardens sustained soil fertility better than monocropping systems. The observed variations in soil physicochemical properties among different land use types indicate a threat to sustainable crop production. Effective management practices aimed at improving soil fertility and sustaining crop production in these altered ecosystems are essential. This study highlights the importance of adopting appropriate management strategies to conserve soil health and ensure sustainable crop production in tropical landscapes like Kerala. The holistic approach adopted in this study, encompassing a wide range of soil fertility parameters across various land uses, along with its implications for sustainable land management, adds significant novelty and relevance to the existing literature on soil dynamics in tropical regions like Kerala.

Spectral noise reduction of double-layer porous asphalt: From laboratory to field

The double-layer porous asphalt (DLPA) pavement is a practical way to mitigate traffic noise from the source. However, there hasn't been much research done on the spectral noise characteristics of the car/truck on this type of pavement with different surface conditions yet. The objective of this paper was to reveal these noise characteristics and the behaviors of the DLPA pavement by laboratory tests and field measurements. First, measurements were made of the road performance of different porous asphalt (PA) mixtures and DLPA structures. Then, a vector impedance measurement system was utilized to evaluate the effects of porosity, aggregate size, and thickness on the sound absorption coefficient (SAC) of the DLPA slabs. Third, a sound meter was used to record the noise levels outside/inside the car/truck on the roads with three surface conditions for the DLPA (PA-10+PA-20) and stone matrix asphalt (SMA) test section, which were paved on an elevated urban road. Finally, an analysis was done on the overall and spectral noise characteristics. The results demonstrated good road performance of these PA mixtures and DLPA structures. Relatively fine and coarse aggregates in the upper and lower layers, respectively, enhanced the sound absorption. But an increase in porosity beyond 20 % and a slight variation in thickness did not considerably improve the sound absorption. Compared to SMA pavement, the overall noises levels of the DLPA pavement were 4–8 dBA lower on the “dry” surface and 6 dBA lower on the “wet” surface. The DLPA pavement exhibited a noise reduction at the full frequency band, which attributed to the pore structure and the relatively fine aggregate used. The interior sound energy always concentrated on the low-frequency band. However, the exterior sound energy on the “dry” and “wet” road surfaces tended to the low-frequency and high-frequency bands, respectively. These findings would shed light on the spectral noise characteristics of the DLPA pavement and provide a new knowledge about the behaviors of the lower layer and upper layer in relation to noise reduction and road performance.

Unveiling the anion-specific effect induced structure and behavior variations on a single chitin chain

Ion-specific effects have a profound impact on the macroscopic properties of polysaccharides such as the aggregation and solubility in solutions. However, the underlying molecular mechanisms still require exploration. In this study, we investigated the influence of anions on the structure and behavior of chitin via a combination of single-molecule techniques and macroscopic characterizations. Our findings reveal that the hydration of anions functions as bridging center, leading to the formation of water-ion-water bridges between chitin side groups. Remarkably, this structure exhibits a binding affinity to chitin following the Hofmeister series with the order of F− < Cl− < Br− < I−, resulting in an escalating of left-handed helix order of chitin. Subsequent experiments indicate that the bridging structure affects the size of chitin aggregates in the similar manner, implying the impact of anions on the structure and behavior of chitin across length scales. These results provide valuable insights into the understanding of ion-specific effects on polysaccharides and its applications in food science where high salt environments are involved.

Edaphic influences on soil organic carbon in the forest systems of southern Western Ghats, India.

Spatial distribution and edaphic influences on soil organic carbon (SOC) are key determinants of carbon sequestration potential, and analysis of aggregate-protected SOC gives an in-depth understanding of the stability of carbon stored in soils. The present study evaluated the edaphic effects on the SOC in four different forest types-tropical evergreen forest, tropical moist deciduous forest, tropical dry deciduous forest and shola forest-in the southern high hills agro-ecological zone of Western Ghats, India. SOC stocks at depths of up to 1m varied significantly across forest types, with the highest levels observed in the shola forest type (441.08Mg C/ha) and the lowest in the dry deciduous forest (138.17Mg C/ha). Around 70% of SOC was found in upper layers (0-30cm) in all the studied forest types. Evaluation by a fixed-effect model showed that forest type, soil depth and aggregate size significantly affected SOC storage in these systems. An assessment of the relative importance and effect of 14 edaphic factors on SOC content in different forest types using the random forest model showed that the algorithm could explain 93.68%, 41.72%, 45.53% and 75.2% variability of SOC concentration across shola, dry deciduous, moist deciduous and evergreen systems, respectively. Across all forest types, except for dry deciduous forests, soil texture was found to be the primary factor influencing SOC, surpassing all other edaphic parameters. Ionic interactions by way of metal oxides like Ca2+, Al3+, Fe3+, Mg and H+ influenced the SOC in tropical forest systems. The insights into SOC dynamics and the edaphic factors regulating them offer valuable guidance for forest management in tropical regions, particularly regarding climate change mitigation.